Composite materials created by forming crystal structures around carbon nanotubes

Leslie Rubinstein*

This presentation describes a material structure that consists of tubular crystal structures formed around carbon nanotubes in order to form extremely strong composite materials.

There are a number of problems with forming single crystal macro-sized structural members. One of the foremost is getting the crystals to be large enough and the correct shape. Various methods have been used to get around this problem, such as growing crystals the same way that semiconductor crystals are made, or by sintering, as is the case with tungsten carbide. Unfortunately, there are problems associated both with the manufacturing techniques and with the resulting materials. In the case of tungsten carbide and similar materials, extreme hardness can be achieved but at the result of extreme brittleness. This is made even more apparent as a result of case and surface hardening techniques applied to various steels. While the techniques can be used, they are still not perfect and can result in overly brittle or otherwise defective or limited materials. The use of carbon nanotubes for extreme longitudinal strength is used to overcome one of the major problems of single crystal macro-sized strength members; to wit, the difficulty in forming flawless crystals of the requisite size and shape. The crystal structures provide tremendous shearing and compressive strength while the nanotubes provide longditudinal strength, resulting in uniquely strong and durable materials without the attendant brittleness and other effects previously encountered in single-crystal materials.

Another problem with extremely aligned and single-crystal materials is that, in the case of steels, one will end up with a really powerful magnet, since in a single crystal all of the magnetic domains are lined up and reinforcing each other. In the case of nanotube-reinforced structures, the crystal shapes can be chosen so that the magnetic domains are not aligned, resulting in a magnetically neutral structure.

We will present several possible overall structures and crystal structures, and also discuss manufacturing methods.